# ST_NumPoints function

The ST_NumPoints function takes a geometry as an input parameter and returns the number of points that were used to define that geometry. For example, if the geometry is a polygon and five points were used to define that polygon, then the returned number is 5.

If the specified geometry is null or is empty, then null is returned.

## Syntax

## Parameter

- geometry
- A value of type ST_Geometry or one of its subtypes that represents the geometry for which the number of points is returned.

## Return type

INTEGER

## Example

A variety of geometries are stored
in the table. The ST_NumPoints function determines how many points
are within each geometry in the SAMPLE_GEOMETRIES table.

```
CREATE TABLE sample_geometries (spatial_type VARCHAR(18), geometry ST_Geometry)
INSERT INTO sample_geometries
VALUES ('st_point',
ST_Point (2, 3, 0) )
INSERT INTO sample_geometries
VALUES ('st_linestring',
ST_LineString ('linestring (2 5, 21 3, 23 10)', 0) )
INSERT INTO sample_geometries
VALUES ('st_polygon',
ST_Polygon ('polygon ((110 120, 110 140, 120 130, 110 120))', 0) )
SELECT spatial_type, ST_NumPoints (geometry) NUM_POINTS
FROM sample_geometries
```

Results: ```
SPATIAL_TYPE NUM_POINTS
--------------- ----------
st_point 1
st_linestring 3
st_polygon 4
```